C-Kit in Atherosclerosis

 描述（由申请人提供）：尽管降脂药物和旨在降低胆固醇水平的生活方式改变取得了所有进展，但动脉粥样硬化是美国死亡和疾病的主要原因。动脉粥样硬化是一种慢性疾病，导致斑块在动脉壁中积聚。表型转换后从中膜迁移的平滑肌细胞（SMC）显著促进动脉粥样硬化和斑块稳定性。然而，在疾病发展中负责SMC表型调节的分子机制仍然不清楚。因此，我们假设c-Kit信号稳定了动脉壁的SMC收缩表型，这控制了早期动脉粥样硬化疾病的进展，并降低了晚期病变斑块破裂的风险。我们支持这一假设的初步研究表明：1）c-Kit在健康和患病的人类和小鼠动脉粥样硬化中的表达，2）c-Kit在SMC表型转换中的作用，3）SCF或c-Kit功能受损的高血压小鼠的全身动脉粥样硬化增加，以及4）c-Kit缺陷小鼠易损斑块破裂的风险增加。我们将在三个具体目标中证明我们的假设。在目标1中，我们提出测试是否c-Kit的功能的SMC的损失或增益改变动脉粥样硬化的发展在高血脂症小鼠。我们将利用一种新的基因工程小鼠和一种新设计的诱导型慢病毒载体来抑制或激活动脉平滑肌细胞中的c-Kit基因。在目标2中，我们将研究c-Kit维持SMC收缩表型的分子机制。我们将使用来自c-Kit条件性敲除小鼠的培养细胞来证明c-Kit/PI 3 K/Akt信号传导轴和DUSP介导的MAPK去磷酸化在维持SMC收缩基因转录中的相关性。最后，在目标3中，我们将研究改变血管c-Kit信号传导在体内血管炎症和动脉粥样硬化斑块破裂中的影响。我们将评估在喂食他莫昔芬以使斑块中的c-Kit基因消失后，喂食HFD的条件小鼠中的自发斑块破裂。总之，这些研究将推进我们对c-Kit在动脉粥样硬化中作用的认识，并将提供新的治疗靶点，以预防并最终减轻动脉粥样硬化的破坏性影响。

 DESCRIPTION (provided by applicant): Atherosclerosis is the leading cause of death and illness in the United States despite all advances in lipid- lowering drugs and lifestyle changes designed to reduce cholesterol levels. Atherosclerosis is a chronic disease that causes accumulation of plaques in the arterial walls. Smooth muscle cells (SMCs) that migrate from the media after phenotypic switching significantly contribute to atherosclerosis and plaque stability. However, the molecular mechanisms responsible for SMC phenotypic modulation in disease development still remain unclear. Consequently, we hypothesize that c-Kit signaling stabilizes the SMC contractile phenotype in arterial walls, which controls the progression of the disease in early atherosclerosis and decreases the risk of plaque rupture in advanced lesions. We support the hypothesis with preliminary studies that demonstrate: 1) the expression of c-Kit in healthy and diseased human and mouse aortas, 2) the role of c-Kit in SMC phenotypic switching, 3) increased systemic atherosclerosis in hyperlipidemic mice with impaired SCF or c-Kit functions, and 4) increased risk for vulnerable plaque rupture in c-Kit deficient mice . We will prove our hypothesis in three specific aims. In aim 1 we propose to test whether c-Kit loss or gain-of-function in SMCs alters atherosclerosis development in hyperlipidemic mice. We will make use of a novel genetically engineered mouse and a newly designed inducible lentivector to inactivate or activate the c-Kit gene in arterial SMCs. In aim 2 we will examine the molecular mechanisms by which c-Kit maintains the contractile phenotype in SMCs. We will use culture cells from c-Kit conditional knockout mice to demonstrate the relevance of the c- Kit/PI3K/Akt signaling axis and DUSP mediated dephosphorylation of MAPK in maintaining the transcription of SMC contractile genes. Finally, in aim 3 we will investigate the impact of altering vascular c-Kit signaling in vascular inflammation and atherosclerotic plaque rupture in vivo. We will evaluate spontaneous plaque rupture in HFD fed conditional mice after tamoxifen feeding to inactivate the c-Kit gene in the plaque. Together, these studies will advance our knowledge about the role of c-Kit in atherosclerosis and will furnish new therapeutic targets to prevent and eventually mitigate the devastating effects of atherosclerosis.